Lift truck mast-mounting arrangement

ABSTRACT

A mounting device for a tiltable lift truck mast in the form of a pair of bearing-supported pivot pins which are engaged in upwardly-opening, concave bearing surfaces of corresponding hanger brackets is provided. Each hanger bracket further includes a retainer in the form of a bolt and sleeve having a tapered end portion. Each retainer is cooperable with an annular groove in a respective pivot pin to prevent both rotational as well as axial movement of the pin with respect to its hanger bracket. Alternatively, pin movement is prevented by a bolt extending through a transverse bore in the pin.

United States Patent [19] Murphy et al.

[ LIFT TRUCK MAST-MOUNTING ARRANGEMENT [75] Inventors: James W. Murphy,Wickliffe;

Robert J. Frantz, Brooklyn; Harold V. Hildebrecht, Cleveland, all ofOhio [73] Assignee: Towmotor Corporation, Cleveland,

Ohio

[22] Filed: Apr. 24, 1972 [21] Appl. No.: 246,782

52 user. 214/674 51 Int. Cl B66f 9/20 58 FieldofSearch ..214/145, 620,670,

[56} References Cited UNITED STATES PATENTS Weaver 214/674 Jan. 1, 19743,054,522 9/1962 Peck 214/674 Primary Examiner-Gerald M. ForlenzaAssistant Examiner Lawrence J. Oresky Attorney-Martin Majestic et a1.

57 ABSTRACT A mounting device for a tiltable lift truck mast in the formof a pair of bearing-supported pivot pins which are engaged inupwardly-opening, concave bearing surfaces of corresponding hangerbrackets is provided. Each hanger bracket further includes a retainer inthe form of a bolt and sleeve having a. tapered end portion. Eachretainer is cooperable with an annular groove in a respective pivot pinto prevent both rotational as well as axial movement of the pin withrespect to its hanger bracket. Alternatively, pin movement is preventedby a bolt extending through a transverse bore in the pin.

12 Claims, 6 Drawing Figures PATENTED JAN 1 74 sum 3 OF 3 LIFT TRUCKMAST-MOUNTING ARRANGEMENT BACKGROUND OF THE lNi/ENTION The instantinvention relates generally to lift trucks and, in particular, to animproved mast-mounting arrangement for pivotally supporting the mastassembly.

Lift trucks generally comprise a motor-driven chassis having a mastassembly pivotally attached to the front end thereof by a mast-mountingarrangement or means. The mast-mounting arrangement typically comprisesa pivot shaft desirably located as low on the chassis as possible suchthat the mast assembly is as close to the chassis center of gravity aspossible in order to minimize tipping of the vehicle during loadhandling.

Typically, the vehicle differential is located at the front end of thevehicle in order to power the front wheels. Due to the rather large sizeof the differential, the desired location of the mast assembly isprevented if a single pivot shaft is used. This has led to the use of apair of pivots mounted on the vehicle chassis on opposite sides of theprojecting differential. However, this type of arrangement has not beenentirely satisfactory for several reasons.

These prior art mast-mounting arrangements generally contain a largenumber of parts which are both co'stlyas well as difficult to assembleand remove when it becomes necessary to remove the mast assembly fromthe vehicle. These arrangements generally comprise a half bearing and aretainer together with a plurality of bolts for securing the pivot pinor shaft within the half bearingby means of the retainer.

Also contributing to difficulty in assembly and removal encountered withthe prior. art mast-mounting arrangements is the location of sucharrangements in the confined space between the mast assembly and thevehicle front end. The plurality of bolts securing the retainers arenormally reached either from above or below the vehicle, in either casewith great difficulty.

Attempts have been made to solve these and other prior art problems. Forexample, the mounting arrangement shown in US. Pat. No. 3,321,044, toLinsay utilizes a pair of pivot shafts but still requires the pluralityof bolts associated with each pivot to be installed and removed from theconfined space between the mast assembly and the chassis.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, the primaryobject of this invention to provide an improved lift truck mast-mountingarrangement.

It is a further object of this invention to provide a lift truckmast-mounting arrangement which places the mast assembly close to thevehicle center of gravity.

it is a further object of this invention to provide a lift truckmast-mounting arrangement permitting easy removal and installation ofthe mast assembly to be accomplished.

The instant invention takes the form of a pair of upwardly-directed,generally hook-shaped hanger brackets mounted on the vehicle chassis onopposite sides of the differential housing. Each bracket defines an upwardly-directed, elongated slot portion useful for indexing amast-mounted pivot pin during installation of the mast on the vehicle aswell as a concave bearing portion cooperable with the pivot pin. Eachpivot pin is rotatably supported at each end thereof by bearings whichare, in turn, supported by the arms of a mast bracket mounted on themast assembly. A retainer in the form of a sleeve-mounted bolt isassociated with each hanger bracket. A tapered end portion on the sleeveis cooperable with an annular groove intermediate the ends of the pivotpin to prevent both rotary as well as axial movement of the pivot pin aswell as securing the pin in engagement with the concave bearing surface.

In an alternate embodiment, pin movement is prevented by a boltextending through a transverse hole in the pin.

Other objects and advantages of the invention will become apparent fromthe following drawings and description.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view of alift truck em bodying the instant invention;

FIG. 2 is a top plan view, in partial cross section, taken along lines2-2 in FIG. ll;

FIG. 3 is an enlarged side elevational view of a single pivot in partialcross section taken along lines 3-45 in FIG. 2;

FIG. 4 is a top plan view of the same taken along lines 44 in FIG. Ii;

FM]. 5 is an enlarged side elevational view of a sec ond embodiment of asingle pivot in cross section similar to FIG. 3; and

FIG. 6 is a top plan view of the same similar to lFlG. 4.

BRlEF DESClRlPTlON FIG. 1 shows generally at iii? a fork-lift trucltcomprising a chassis l2 containing motor means (not shown) in the areagenerally shown at id. An operator station generally shown at in isprotected by means of a roll-over protection structure llh.

Ground-engaging, front drive wheels 20 and rear wheels 22 support thevehicle for movement over the ground-support surface. A lift mastassembly 24 comprising a plurality of pairs of vertically telescopinglift masts 26, 28 movably support a carriage 30 having a pair of liftforks 32 mounted thereon in the conventional manner. Articulation of thelift mast assembly about the mast-mounting arrangement shown generallyat 3d is accomplished by means of a pair of hydraulic jacks, one ofwhich is shown at 36, pivotally connecting the chassis with the tiltablelift mast assembly 2d.

Turning now to H6. 2., the structure and relationship of themastmounting arrangement or means 3d as well as its relationship toother components can be more readily discerned. The mast-mountingarrangement is shown to comprise a pair of identical pivot assemblyunits 38 located on opposite sides of differential housing 40. Eachpivot assembly unit is fastened to both the mast assembly 2% as well asa laterally-oriented member 42 of the front axle assembly.

Referring now to FIGS. 3 and Al, one of the pairs of pivot assemblyunits will be described for the sake of illustration. The unit comprisesa generally hookshaped hanger bracket Ml defined by an upwardlyopening,elongated slot 46 and a convex or arcuate bearing surface 48. Bearingsurface dd is dimensioned to conform to the generally-cylindrical pivotpin or shaft 50 over of its outer periphery. The hanger bracket may beconveniently constructed of cast or formed metal such as iron or steelso as to have a rear recess 52 therein as well as an axially alignedbore 54 in an upward projection 56 for a purpose to be more fullydescribed below.

In like manner, a mast bracket 58 having bifurcated arms 60 extendingfrom a base 62 may be similarly constructed. As perhaps best seen inFIG. 4!, the mast bracket 58 has a pair of axially-aligned bores 64contained within the outer ends of the arms 60. Fitted within bores 64in a conventional manner are concentric sleeve bearings 66. Pivot pin 50is concentrically located within the bearings and dimensioned to berotatable relative thereto. A pair of O-ring seals 68 of resilientmaterial such as rubber are contained within spaced, annular grooves inthe periphery of pin 50 which is conveniently of metal material, e.g.,steel. These O-rings act as seals to retain beaing lubricant and keepout deleterious abrasive material.

A retainer shown generally at 76) is provided in the form of a bolt 72having a head and a threaded end portion 74 which is threadably engagedin a bore 76 in hanger bracket 44. A sleeve 78 around the bolt has atapered end portion 80 which is cooperable within an annular groove 82around pin 50 and intermediate the ends thereof. The described elementsare dimensioned such that the tapered portion 80 contacts the groove 82such that rotational and consequent axial movement of the bolt resultsin retainer 70 preventing rotational as well as axial movement of thepin. Such torquing may be accomplished from the front of the vehiclethrough concentric apertures 34, 86 in carriage plate 88 and base 62,respectively. As best seen in P16. 4, arms 60 are dimensioned to closelyencompass hanger bracket 44 such that lateral movement of the mastassembly with respect to the chassis is minimized. With pivot pin 50held in engagement with bearing surface 48, the pivot pin will bestationary with respect to the chassis, and the mast assembly will pivotabout the pin through the operation of the bearings 66.

In assembling mast assembly 24 onto chassis 112, the O-rings 68 arefirst installed on each pivot pin 50. The pivot pins are then insertedin mast brackets 58 with the ends thereof fitted within bearings 66. Themast assembly 24, upon which mast brackets 58 are mounted, is thenlowered such that the pivot pins 50 are guided into engagement withbearing surfaces &8 by means of slot 46, as seen in FIG. 3. A retainer70 is then inserted through apertures 84, 86 from the front of thevehicle. The bolt '72 having threaded portion 74 is then threadablyengaged in bore 76 but not tightened. Pivot pins 50 are then laterallypositioned so as to align annular grooves 82 therein with taperedportion 80 of sleeve 78. Bolts 72 are then tightened to a predeterminedtorque to secure the mast assembly to the chassis. Removal of the mastassembly is accomplished by reversing the steps.

Referring now to FIGS. and 6, a second embodiment of the invention isshown in which structure finding its numerical analogue in the firstembodiment is prefaced with the numeral one. The parimary distinctionover the first embodiment is in using a bolt 172 extending through aclosely-fitting lateral bore 88 in pin 150 so as to be engageabletherewith. Slots 96B are provided at each end of pin 150 for indexingpurposes as will be hereinafter described. A bolt locking means such asbolt lock 92 serves to prevent unwanted removal of the bolt 172.

Assembly is accomplished in similar manner to that described with thefirst embodiment. After guiding the pivot pins 150 into bearing surfaces148, the pins are moved axially by tapping and indexed by inserting ascrewdrive or other tool (not shown) into slots to achieve alignment ofbores 154,176 and 88. After bolt 172 is inserted into the aligned boresand tightened, a tab 94 on bolt lock 92 is bent over, as shown, againstthe bolt head to secure the bolt in place.

It is to be understood that the foregoing description is merelyillustrative of the preferred embodiments of the invention and that thescope of the invention is not to be limited thereto, but is to bedetermined by the scope of the appended claims.

What is claimed is:

1. In a lift truck having a chassis and a mast assembly, a mast-mountingarrangement pivotally attaching the mast assembly to the chassis, saidmast-mounting arrangement comprising:

a pair of hanger brackets on said chassis each defining a generallyconcave bearing surface,

a pair of mast bracket means on said mast assembly having means thereonrotatably supporting a pair of shafts, each of said shafts being incomplementary engagement with a respective one of said concave bearingsurfaces, and

retention means on each of said hanger brackets for preventing bothrotational as well as axial move ment of said shafts with respect tosaid hanger brackets.

2. The invention of claim ll wherein each of said hanger bracketscomprises a generally hook-shaped member defined by an elongated slotportion and said concave bearing portion.

3. The invention of claim il wherein each of said mast bracket meanscomprises a base and a pair of arms in spaced relation extending fromsaid base.

4. The invention of claim 3 wherein said mast bracket means furthercomprises a bore through each arm and wherein said means rotatablysupporting said shafts comprise bearing means in said bores.

5. The invention of claim 4 wherein said bearing means comprisegenerally-cylindrical sleeve bearings fitted within said bores.

6. The invention of claim )1 wherein each of said shafts comprises agenerally-cylindrical member defining a pair of end portions and acenter portion intermediate said end portions, and wherein said endportions are rotatably fitted within said bearings.

'7. The invention of claim 6 further including seal means for retaininglubricant in said bearings and for excluding foreign matter.

8. The invention of claim 3. wherein each of said retention meanscomprise sleeve means defining a tapered end portion and means fortightening said sleeve means against said shaft whereby said shaft isheld against said concave bearing surface.

9. The invention of claim 8 wherein each of said shafts has an annulargroove therearound intermediate its ends, and wherein said retentionmeans is located to position said sleeve means tapered end portion insaid groove.

10. The invention of claim ll wherein said retention means comprise atransverse bore through each of said shafts and bolt means extendingthrough said transverse bore, said bolt means being secured to arespective hanger bracket.

11. The invention of claim it further including lock means for securingsaid bolt means.

12. The invention of claim 3 wherein said retention means comprise atransverse bore through each of said shafts and means in said transversebore extending through an axially aligned bore in said hanger bracket.=t =C= =i=

1. In a lift truck having a chassis and a mast assembly, a mastmountingarrangement pivotally attaching the mast assembly to the chassis, saidmast-mounting arrangement comprising: a pair of hanger brackets on saidchassis each defining a generally concave bearIng surface, a pair ofmast bracket means on said mast assembly having means thereon rotatablysupporting a pair of shafts, each of said shafts being in complementaryengagement with a respective one of said concave bearing surfaces, andretention means on each of said hanger brackets for preventing bothrotational as well as axial movement of said shafts with respect to saidhanger brackets.
 2. The invention of claim 1 wherein each of said hangerbrackets comprises a generally hook-shaped member defined by anelongated slot portion and said concave bearing portion.
 3. Theinvention of claim 1 wherein each of said mast bracket means comprises abase and a pair of arms in spaced relation extending from said base. 4.The invention of claim 3 wherein said mast bracket means furthercomprises a bore through each arm and wherein said means rotatablysupporting said shafts comprise bearing means in said bores.
 5. Theinvention of claim 4 wherein said bearing means comprisegenerally-cylindrical sleeve bearings fitted within said bores.
 6. Theinvention of claim 1 wherein each of said shafts comprises agenerally-cylindrical member defining a pair of end portions and acenter portion intermediate said end portions, and wherein said endportions are rotatably fitted within said bearings.
 7. The invention ofclaim 6 further including seal means for retaining lubricant in saidbearings and for excluding foreign matter.
 8. The invention of claim 1wherein each of said retention means comprise sleeve means defining atapered end portion and means for tightening said sleeve means againstsaid shaft whereby said shaft is held against said concave bearingsurface.
 9. The invention of claim 8 wherein each of said shafts has anannular groove therearound intermediate its ends, and wherein saidretention means is located to position said sleeve means tapered endportion in said groove.
 10. The invention of claim 1 wherein saidretention means comprise a transverse bore through each of said shaftsand bolt means extending through said transverse bore, said bolt meansbeing secured to a respective hanger bracket.
 11. The invention of claim10 further including lock means for securing said bolt means.
 12. Theinvention of claim 1 wherein said retention means comprise a transversebore through each of said shafts and means in said transverse boreextending through an axially aligned bore in said hanger bracket.